The striking new finding of neuronal mitochondrial hypertrophy and reduction of cerebral edema in ischemic gerbils treated with the vasoactive drug Pentoxifylline has been found to be statistically significant for the occlusion, survival and treatment times chosen for the earlier part of the study (cf. Progress Report). Accordingly, it is proposed to extend the above studies by following the time course of the ultrastructural phenomena at closely spaced intervals from 2 to 120 hours' survival time. Cortical brain slices from drug-treated ischemic animals will be studied with respect to a number of biochemical processes related to oxidative metabolism and to energy production and utilization.